The present invention relates to an automatic conveyance apparatus for a document in a copying machine such as an machine, and particularly to the mechanism for replacing a document-conveying endless belt.
A document conveyance apparatus is normally used, after being installed on the document table of a copying machine or the like, to convey the sheet type documents (hereinafter called a document) automatically. When it is in an open state, the manual operation for documents is possible.
Documents loaded on the document feeding table (sheet feeding tray) are fed out one by one by means of a sheet-feeding section of a document conveyance apparatus, and each of them is fed and positioned, by means of a conveyance belt in the conveyance section, on the document-placing table glass (platen glass) where the document is exposed to light from the exposure lamp provided in the main body of a copying machine, and then is further ejected onto the document-exit tray.
On a document conveyance apparatus such as this, there are provided many rollers rotatably supported on frame side plates, such as, for example, conveyance rollers composed of a belt-driving roller, a driven roller, a tension roller, a pressure roller or the like as well as a sheet-feeding roller and a sheet-exit roller. A conveyance belt composed of one or a plurality of belts used for the conveyance of a document is spread between the aforesaid conveyance rollers.
In such a mechanism of a document conveyance apparatus, when removing and replacing the aforesaid conveyance belt and various rollers on the occasion of assembly, periodic inspection or apparatus troubles, there have been required complicated procedures and much labor and time have been consumed and it has been difficult to keep the assembling accuracy stably. In particular, the surface of the aforesaid conveyance belt which must be kept white constantly needs to be replaced with a new one occasionally, because it is easily soiled and scratched while it is used. Further, after the conveyance belt is used for a long time, it also needs to be replaced with a new one because of its deformation and change in quality.
In one of the conventional methods for replacing a conveyance belt, the outer casings of a document conveyance apparatus are removed first, then bearings and others are removed from the roller-supporting side plate, and all rollers passing through the inside of a loop shaped conveyance belt are removed, thereby the loop of a conveyance belt is released.
In this method, the side plate of a frame is separated in advance occasionally. Further, a driving roller naturally needs to be removed. Therefore, a mechanism for separating the driving roller from the driving system needs to be prepared, which causes a complicated mechanism and difficult work.
Even in the case of a document conveyance apparatus of a monocoque structure type wherein outer casings play a role of a structural member, bearings for each roller, various panels located at the bottom of an apparatus and casings need to be removed first, and then, all rollers are removed for the replacement of a conveyance belt.
Furthermore, when replacing a conveyance belt, a driven roller and others need to be moved for adjusting to a proper belt tension because there is a difference between the incoming and outgoing conveyance belts in terms of a total length of an endless belt. Even in this case, disassembling work identical to the above has been needed.
From the viewpoint of an easy process for replacing a conveyance belt and rollers and of an assurance of functions after the replacement, it is desired that the replacing work is easy, the time required for the replacement is short and readjustments for sensors and parts are not needed. Namely, the mechanism that makes a simple and efficient replacement possible is desired.
The conventional mechanism, however, does not always satisfy fully the above desired points due to its weak points mentioned previously.